Adsorbent for aromatic isomers and production of aromatic isomers

Abstract

An adsorbent which comprises a zeolite containing Cs and/or Rb, said zeolite being characterized by that the ratio of [the number of moles of Cs and/or R in the zeolite] to [the number of moles of Al in the zeolite] is 0.1 or less. This adsorbent permits efficient separation of an isomer from a mixture of aromatic isomers.

What is claimed is:  
     
       1. A process for production of aromatic isomers which comprises separation of at least one species of isomer from a mixture of halogenated aromatic isomers using an adsorbent which is a zeolite containing Cs and/or Rb, said zeolite being characterized in that the ratio of (the number of moles of Cs and/or Rb in the zeolite) to (the number of moles of Al in the zeolite) is 0.1 or more, wherein the halogenated aromatic isomer is a disubstituted halogenated aromatic isomer represented by the following formula:                    
       (where X denotes a C 1-6  alkyl group or a halogen, and Y denotes a halogen.). 
     
     
       2. A process for production of halogenated aromatic isomers as defined in claim  1 , wherein the disubstituted halogenated aromatic isomer is chlorotoluene or dichlorobenzene. 
     
     
       3. A process for production of aromatic isomers as defined in claims  1  or  2 , which employs a desorbent composed mainly of a halogen-free aromatic compound. 
     
     
       4. A process for production of aromatic isomers as defined in claim  3 , wherein the desorbent is composed mainly of xylene. 
     
     
       5. A process for production of aromatic isomers as defined in claim  1 , wherein the zeolite is zeolite Y and the desorbent is one which is composed mainly of m-xylene, and m-isomer is separated as the raffinate component from a mixture of disubstituted halogenated aromatic isomers. 
     
     
       6. A process for production of aromatic isomers as defined in claim  1 , wherein the zeolite is zeolite Y and the desorbent is one which is composed mainly of p-xylene, and m-isomer is separated as the extract component from a mixture of disubstituted halogenated aromatic isomers. 
     
     
       7. A process for production of aromatic isomers as defined in claim  1 , wherein the zeolite is zeolite Y, the adsorbent is one which contains K and/or Ag, and the desorbent is one which is composed mainly of m-xylene, and m-chlorotoluene is separated as the raffinate component from a mixture of chlorotoluene isomers. 
     
     
       8. A process for production of halogenated aromatic isomers as defined in claim  1 , wherein the zeolite is zeolite Y, the adsorbent is one which contains K and/or Pb, and the desorbent is one which is composed mainly of m-xylene, and m-dichlorobenzene is separated as the raffinate component from a mixture of dichlorobenzene isomers.